Automotive saddle fuel tanks have a tank shell configured with a centrally disposed bight in the bottom thereof. The bight provides an exterior concavity which is intended to provide accommodation for drivetrain and/or exhaust components of the motor vehicle to pass freely therethrough. While providing free space at the exterior of the tank shell, the bight also provides a riser within the fuel tank which effectively creates two sumps on either side thereof, wherein the two sumps conjoin in the space of the fuel tank higher than the height of the riser. In view of the presence of the bight, wherein the riser creates two separated sumps, attention must be carefully given to the fuel extraction system.
FIG. 1A is a sectional schematic view of a conventional saddle fuel tank 10. The tank shell 12 defines a bottom 14 and an oppositely disposed top 16, wherein a bight 15 provides a concavity 18 exterior to the fuel tank and a riser 20 interior to the fuel tank, in turn providing a primary sump 22 and a secondary sump 24.
The saddle fuel tank 10 has a fuel extraction system in the form of a single modular reservoir assembly (MRA) 25. The top 16 of the tank shell 12 carries primary and secondary modular reservoir assembly (MRA) covers 26, 28, wherein the primary MRA cover is a part of the single MRA 25. An inlet check valve 30 provides an entry for fuel into the fuel tank 10, wherein the primary sump 22 is identified as the sump first filled by fuel introduced from the inlet check valve. An in-tank disposed electric fuel pump 32, when energized, pumps fuel from the primary sump 22, through a strainer 35, and, via a feed line 34, out of the fuel tank through the primary MRA cover 26, and, via a feed line 36 to a fuel filter 38 situated in a filter assembly 40, whereby the fuel is then filtered by the fuel filter 38.
Fuel which is not used by the engine is returned, via a return port 42 on the fuel line 44 upstream of the filter 38, to the fuel tank 10 through the primary MRA cover 26 and, in turn, through a return line 46, to an in-tank pressure regulator 48. The in-tank pressure regulator 48 maintains a set pressure of the fuel in the fuel line 44 upstream of the return port 42, and bypasses fuel via a return line 50 to a scavenge jet pump 52. The scavenge jet pump 52 scavenges bulk fuel 54 into a primary sump reservoir bucket 56, wherein the bucket is connected to the primary MRA cover 26 by rods (not shown). Additionally, feed fuel from the electric pump 32 is bled off via a bleed line 58 to run a transfer jet pump 60. The transfer jet pump 60 draws fuel from the secondary sump 24 via a transfer line 62 into the primary sump reservoir bucket 56.
The aforedescribed saddle fuel tank fuel system is limited by the fact that only one pump can be placed at the primary sump, since the primary and secondary MRA covers are only 4.5 inches in diameter.
What remains needed in the art is a dual electric pump saddle tank fuel extraction system which avails itself of both the primary and secondary sumps for fuel extraction system packaging, wherein fuel is continually available to both electric pumps without starving one before the other when fuel becomes depleted.